Oil recovery method



Nov. 20, 1962 D. c. LINDLEY OIL RECOVERY METHOD Filed Dec. 8, 1959 INVENTOR. DONALD C LIN DLEY,

ATTORNEY.

United States Patent O 3,064,729 OIL RECOVERY METHOD Donald C. Lindley, Houston, Tex., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla, a corporation of Delaware Filed Dec. 8, 1959, Ser. No. 858,241 2 Claims. (Cl. 166-9) The present invention is directed to a method for completing and producing oil wells to improve recovery of hydrocarbons from subsurface reservoirs. The method is especially adaptable for use with small steeply inclined reservoirs.

The method of the invention may be used to recover both attic and cellar oil. In the case of attic oil, production problems arise because the well is off production because water has encroached up structure which watered out the perforations through which the oil had been produced. When this happens, it is desirable to force the water and oil down structure by injecting gas. In the case of cellar oil, production problems arise because the well is dead because solution gas-drive has ceased and there is no active water-drive to maintain reservoir pressure. In this instance, it is desirable to inject water to raise reservoir pressure and force the cellar oil upward.

The problems associated with recovery of attic and cellar oil are more pronounced with small steeply inclined reservoirs. One solution to these problems is to drill two wells, one down-dip of the other, so that the formation oil may be produced either by gas-cap drive from above through the up dip well or water flooding from below through the down-dip well. However, this solution is not satisfactory because the cost of drilling two wells is usually prohibitive especially in the case of the small size reservoir.

My invention solves the problem at a fraction of the cost of providing two separate wells. This solution is providing two wells drilled in the same hole. Upon discovery of a producing formation and a general knowledge of the geometry of the reservoir determined, one well may be deviated from another well penetrating the reservoir by whip stocking some place along the well bore of the other well and drilling in a manner to penetrate the reservoir further down-dip. The well may be completed employing multiple tubingless completion techniques which permit a string of tubing to enter each of two down hole wells and be completed independently. Once the strings of tubing are in position, the reservoir may be produced efliciently by gas or water-drive.

Thus, a primary object of the present invention is to provide an improved operation for the recovery of oil from subsurface reservoirs.

The above object and other objects of the invention will be apparent from a more detailed description of the invention taken in conjunction with the drawing wherein:

FIG. 1 is a cross-sectional view of the sub-surface shoWing one manner of operation according to the invention; and

FIG. 2 is a view similar to that shown in FIG. 1 illustrating another manner of operation according to the invention.

Referring to the drawing in greater detail, in FIG. 1 is shown a well bore extending from the earths sur 3,654,729 Patented Nov. 20, 1962 ice face 11 to the upper portion of an oil reservoir 12. A casing 13 has been run, cemented in as illustrated by cement 14, and perforated as at 15. If the well had been producing, the production tubing is pulled. Then, the casing 13 is pierced as at 16 and a drill string is whip stocked into position and a deviated well bore 17 is drilled. The lower end of well bore 17 is down dip of the lower end of well bore 10. The drill string is then pulled and production tubing strings l8 and 19 are run in the well bores. Tubing string 18, provided with a packer 20, is run in well bore 10 and positioned so that the lower end thereof terminates adjacent perforations 15. Tubing string 19 extends through a portion of well bore 10 and then deviates into well bore 17. Once tubing string 19 has been run, it is cemented in, as illustrated by cement 21. Tubing string 19 then is perforated adjacent the lower end thereof as at 22. Thus, first the nondeviated well may be drilled and oil produced through it, and then the deviated well may be drilled. The well is provided with a suitable wellhead 23 and tubing strings 18 and 19 are provided with valve controls 24 and 25, respectively.

The dotted line dividing the reservoir into upper and lower portions serves to illustrate the separation of phases; that is, the upper portion may be gas and the lower portion oil or the upper portion may be oil and the lower portion water. Thus, in operation, if the upper portion is gas, then an inert gas, such as air, nitrogen, or methane, is injected through tubing string 18 to displace and force the oil in the lower portion of the reservoir through perforations 22 and tubing string 19. On the other hand, if the upper portion is oil and the lower portion is water, water is injected through tubing string 19 through perforations 22 to force oil through perforations 15 and up tubing string 18.

A similar situation exists with regard to FIG. 2. However, no casing, other than surface casing, is run and cemented in as in FIG. 1. Thus, surface casing 9 is set and cemented in as at 8. Then, a well bore 10 is extended below the surface casing and drilled to extend from the earths surface 11 to reservoir 12. Then, the drill string is whip stocked and deviated well 17 is drilled, the lower end of which is down-dip of the lower end of well 10. Tubing strings 18 and 19 are then run in wells 10 and 17, respectively, and cemented in, as indicated by cement 7. Tubing string 18 then is perforated, as at 15, and tubing string 19 is perforated as at 22. The operation is the same as that described for FIG. 1.

Having fully described the objects, nature, and operation of my invention, I claim:

1. A method for the recovery of oil from a steeply dipping subterranean oil reservoir comprising:

the steps of drilling a first well sufiiciently deep to set surface casing;

setting surface casing in said first Well;

cementing said surface casing in said first well;

drilling said first well deeper and extending it below said surface casing into said reservoir;

drilling a second well into said reservoir deviated from said first Well, said deviated second well beginning along the length of said first well above said reservoir and terminating in said reservoir at a location 3 I vertically spaced from the lower end of said first well;- 7 arranging a first well pipe in said first 'well extending from the earths surface into said reservoir; arranging a second well pipe in said first and second Wells extending from the earths surface downwardly through the portion of said first well above the beginning of said second well and through said second well into said reservoir;

perforating each of said first and second well pipes in said reservoir; and then pumping fluid downwardly through the well pipe 3!? ranged in one of said first and second wells and displacing oil to and upwardly through the well pipe References Cited in the file of this patent UNITED STATES PATENTS 1,816,260 Lee July 28, 1931 2,281,801 Reynolds et a1. May 5, 1942 2,452,920 Gilbert Nov. 2, 1948 2,821,255 Spearow June 28, 1958 OTHER REFERENCES Garrett et aL: Parallel. Macaroni String Cuts Well mariged the f said first and am i 15 Costs, Petroleum Engineer, pp. B38-B44, January- 1957-. 

